1. Field of the Invention
The present invention relates to a method for manufacturing a bump leaded film carrier type semiconductor device.
2. Description of the Related Art
New semiconductor packages have been developed to correspond to requirements of electronic apparatuses which are of a smaller size, of a smaller weight, of a higher speed and of a higher function. In order to satisfy such requirements, it is necessary to reduce the pitch of inner leads, i.e., portions of leads connected to a semiconductor chip, simultaneously with the adoption of an area array bonding system capable of enlarging the pitch of outer leads.
One typical inner lead bonding (ILB) system is a wire bonding system which, however, cannot correspond to the increased number of multi-pins and the narrowed pitch of pads of the semiconductor chip. Recently, a tape automated bonding (TAB) system has been broadly used to reduce the size of semiconductor devices. In the TAB system, inner leads made of metal foil by etching on an insulating film are bonded to conductive protrusions (bumps) formed on pads of a chip.
One typical area array bonding system is a flip-chip bonding system. In the flip-chip bonding system, solder bumps are formed on an active element surface of a chip, and then, the chip is reversed and is bonded directly to a substrate, thus corresponding to multi-pins and small-pitched pins. In this case, the length of bonded connections is so short that there is an advantage in high speed and low noise.
In the above-described bonding systems, a process for forming barrier metal and bumps on electrode pads of a bare chip is generally required. For example, when solder is applied as bump material for aluminum electrodes, Cr or Ti as an adhesive layer and Cu, Ni, Rh or Pd as a diffusion avoiding layer have to be formed on electrode faces by a sputtering method or an evaporation method. Also, a step for forming bumps made of solder or Au by ball bumps or by plating is required. Further, in the TAB system, a transfer bump system or mesa bump system for bonding bumps formed on inner leads has been suggested.
In order to make use of both of the advantages of the TAB system and the flip-chip bonding system, first prior art bump leaded film carrier type semiconductor devices have been suggested where bumps are formed on a chip facing side of an insulating film (see: JP-A-SH)53-56969, JP-A-HEI5-47847, JP-A-HEI2-229445). This will be explained later in detail.
In the first prior art bump leaded film carrier type semiconductor device, however, outer leads, i.e., portions of leads connected to a substrate extend to the outside, and as a result, there is a disadvantage in size.
Second prior art bump leaded film carrier type semiconductor devices have also been suggested where bumps are formed on a substrate facing side of an insulating film (see: JP-A-HEI4-154136, JP-A-HEI5-82586). In the second prior art bump leaded film carrier semiconductor devices, since outer leads extend toward the inside, the second prior art bump leaded film carrier type semiconductor devices can be reduced in size as compared with the first prior art bump leaded film carrier type semiconductor devices. This will be explained later in detail.
In the second prior art bump leaded film carrier type semiconductor devices, however, the deformation of the insulating film is very large, or the devices are still large in size.